Self-adjusting mechanical tappet



May 5, 1953 J. w. HUMPHREYS SELF-ADJUSTING MECHANICAL TAPPET 2 SHEETS-SHEET 1 Filed Dec. 5, 1949 \NvEN-rosz JoHNW. HuMPH R KY5 Awoanev y 5, 1953 J. w. HUMPHREYS ,637,309

SELF-ADJUSTING MECHANICAL TAPPET Filed Dec. 5, 1949 2 SHEETS-SHEET 2 m JonNW. HuMPnREYs Aw'rozuewrs Patented May 5, 1953 SELF-ADJUSTING MECHANICAL TAPPET John W. Humphreys, Muskegon, Mich., assignor to Johnson Products, Inc., Muskegon, Mich., a

corporation of Michigan Application December 5, 1949, Serial No. 131,209

2 Claims. 1

This invention relates to a novel tappet structure which, in operation, in conjunction with an internal combustion engine with which it is used, is automatically self-adjusting, any tappet noises such as are frequently heard on starting an engine when it is cold being eliminated, and the tappet at all times having bearing engagement against either the lower end of the valve stem of a valve with which it is associated in one type of engine or, with a push rod which, through operative connection and association with a rocker arm, actuates a valve in another kind of engine generally known as valve-inthe-head engines. The tappet is of a mechanical structure, but operates in susbtantially direct similarity to a hydraulic tappet. With the present mechanical tappet of my invention, the cams of the cam shafts which operate the tappets are of the type used with hydraulic tappet installations, and

not with the usual mechanical tappets. Such tappets of the present invention may readily re placehydraulic tappets, getting the same or a better noiselessness of operation. Or such tappets of the present invention may be used in new engines where hydraulic tappets have been previously used at a decrease in cost and with a like elimination of tappet noises at all times during engine operation, there being required with the present mechanical tappet, similar to other mechanical tappets, only an initial adjustment but with the difference that such adjustment made when the engine is cold with prior mechanical tappets leaves a small space of a few thousandths of :an inch between the lower ends of valve stems and the tappets which actuate them lower end of a push rod bear against the upper end of an actuating tappet is also followed in conjunction with the tappet of the present in- ,vention.

. It is a primary object and purpose of this invention to provide a self-adjusting mechanical tappet, more economical to produce than the selfadjusting hydraulic tappets, and which maintains contact between the tappets and engine valve stems or push rods, in accordance with the type of engine in which the tappets are used, and with an elimination of the very short initial period of tappet noises which follows the starting of a cold engine having hydraulic tappets, continuing until the tappets are supplied with oil under pressure, which occurs shortly after the engine is started. It is a further object to provide a self-adjusting mechanical tappet which can be economically produced, be installed as easily as any mechanical tappet and operate to secure the same functions as well and, it is believed, better than hydraulic tappets. A still further object is to provide tappets which are interchangeable with hydraulic tappets, using the same cam shaft and cams that are used with hydraulic tappets while, when the self-adjusting tappet of the present invention is used in place of present mechanical tappets with the differently ground cams now used with such mechanical tappets, the invention of United States Letters Patent No. 2,463,332, granted April 26, 1949, may be incorporated so that the self-adjusting mechanical tappet of the present invention is available for use and for replacing other tappets under substantially all engine conditions.

An understanding of the invention may be had from the following description, taken in connection with the accompanying drawings, in which:

Fig. 1 is an elevation, with parts in vertical section, showing an overhead engine valve and push rod actuation thereof, with the tappet of my invention in vertical section at the lower end of the push rod, and with the parts of the tappets in the positions they occupy when an engine is cold.

Fig. 2 is a vertical section through the tappet and associated parts of its guide showing the parts of the tappet in positions to which they have automatically moved, as the temperature of the engine increases after running, and parts have been elongated by expansion due to rising temperature.

Fig. 3 is a vertical section through a tappet and associated valve lifted by it, showing my invention applied to the mushroom type of tappet.

Fig. 4 is a partial side elevation and vertical section of a tappet made in accordance with my invention where the hydraulic piston pushing mechanism in the upper end portion of the tappet is removed and replaced with the self-adjusting mechanical tappet of my invention, and

Fig. 5 is a horizontal section substantially on the plane of line 55 01" Fig. 3.

Like reference characters refer to like parts in the different figures of the drawings.

Referring to Figs. 1 and 2 of the drawing, the

tappet body is of cylindrical form having walls I closed at one end at 2 where it will bear against the cam of an actuating cam shaft, the body being hollow and open at its upper end nearly to its lower end. Such cylindrical tappet body is guided in a vertical guide 3 either integral with or connected to the engine block.

The body I, between its ends, has an inwardly extending integral annular ring 4 providing a shoulder upon which a disk member 5 rests. Such member 5 has an exterior diameter very slightly less than the interior diameter .of the upper portion of the body I, has a flat under side and, as shown, has an upper side with'two surfaces 6 (which number may be increased) meeting at a diameter or center of the disk 5 and extending outwardly and downwardly therefrom. In practice the angle of the surfaces 6 to the plane of the flat under side will approximate 9, though it may vary slightly therefrom without affecting the operation of the tappet. The two upper surfaces 6 incline upwardly and inwardly toward each other.

In the upper end of the tappet body I, above the lower member 5 is an upper member I also of disk form, but of greater thickness than the member 5, its exterior diameter being the same substantially as the member 5. It is spaced above the lower member 5, and in the space between them, two adjusting members 8 are located which, as shown in Fig. 5, have each an :outline substantially the segment of a circle, the radiusof which is substantially equal to the radius of the members 5 and '3. Such .two adjusting members 8 have inclined under sides or surfaces complementary of the surfaces 6 to ride thereon and at their upper sides surfaces against the member I. The two adjusting members -8 are grooved between their opposite ends and in the groove formed around them a coiled tension spring 9 is located which, normally contracting, will draw the two members 8 toward each other until their straight edges bear against each other as in Fig. 5.

In Fig. 1 the tappet is shown in operative relation .to a push rod II], which has a head IiIa at its lower end of a generally semi-spherical form received in a complementary recess for it in the upper side of the part I. Adjusting screw connection II with the upper end of the push rod is made with one end of the rocker arm I2 which at its other end bears against the upper end of an overhead valve stem I3, the valve I4 being at the lower end of the stem and which is held in closed position by a heavy coiled spring 55. The valve is opened by upward movement of the tappet by a cam on a rotating cam shaft riding against the lower end 2 of the tappet body.

In the initial adjustment when the engine is cold or at a much lower temperature than it will be after it has been operating, the two members 8 will be pulled together, as in Fig. ,5, by the spring 9 around them and, riding upon the upwardly inclined surfaces 6, will separate the two members 5 and I the greatest distance that they are separated in practice. The adjusting screw II in the initial adjustment is then adjusted so that valve I4 is closed, the upper end of the valve stem I 3 bears against the rocker arm, the bearings of the lower end of the adjusting screw II with the upper end of the push rod I8, and of the head Ifia at the lower end of the push rod with the member 7 are snug and without lost motion between them. There is 4 no tolerance of a few thousandths of an inch observed as in usual mechanical tappets to compensate for the longitudinal expansion of the several parts when their temperature rises with the temperature of the engine block when the engine is run.

When the engine is run and its temperature rises, compensation is 'made by the automatic separation of the members 8. In Fig. 1 they are shown together and in Fig. 2 they are separated to their greatest extent. The spring 9 is stretched. It will be noted that the upper side of the member I is at a distance farther below the upper end of the tappet body I in Fig. 2 than it is in Fig. 1. Such separation occurs under the combined pressure force which is exerted by the valve spring I5 whenever the valve I4 is not completely closed together with vibration or shock of the push rod transmitted to the tappet which causes the members 8 to separate, whereupon they are followed by the upper member I until the valve I4 completely closes. When such valve is completely closed the force of the spring I5 is removed, and the spring 9 will hold the members 8 snugly at their upper sides against the lower sides of the member "I and at their lower sides against the inclined plane surfaces 6. When the engine is stopped and cools and its temperature is reduced, the contraction which occurs releases the pressure of the push rod against the member .I and the two members 8 are drawn together by spring 9 and act as a wedge to maintain such upper member I always in contact with the head His. Under all conditions the snug engagement of the lower ends or head Illa of the push rod with the upper member I of the tappet is maintained, and there is no loose motion with resultant tappet noises, but a snug contact at all times, as effective and as continuous as when hydraulic tappets are used.

In Figs. 3 and 4 tappet structures are shown which may be used where the tappets are below the lower ends of valve stems and are directly between such valve stems and the cams of cam shafts which lift them. In Fig. 3, the tappet is shown as of the mushroom type having a hollow body wall Ia and enlarged lower end 2a with an annular shoulder 411 at the lower part of the tappet body within it. The adjusting members 8 and the cooperating disk members 5 are duplicated, being located one over the other and against the uppermost pair of adjusting members .8, the fiat disk I is located within the body. An interiorly threaded sleeve I6 is inserted in the upper end of the body in which a well known form of self-locking adjusting screw I1 is threaded, adapted to bear at the head at its upper end against the lower end of the valve stem I3, having a valve I4 at its upper end, with the usual heavy valve spring I5 to move the valve to closed position when free to do so.

In Fig. 4, the tappet body is of the so-called barrel type same as shown in Figs. 1 and 2. An adapter which is of a cup-like form having cylindrical walls I8 and a bottom I9 is inserted in the upper end of the tappet body I until it reaches the annular ring I4. Within the cylindrical opening surrounded by the walls I8 the automatic adjusting unit consisting of the lower disk memher 5, the upper spaced disk member I and the two movable adjusting members 8, with the contacting spring 9 around them, is installed together with interiorly threaded sleeve I6 and self-locking adjusting screw I'I threaded thereinto. Such barrel and mushroom tappet bodies are Well known in tappets. Of course, by locating the supporting ring or shoulder 4 at a lower level, a duplication of the self-adjusting mechanism, the same as in Fig. 3, may be had. Normally but one series of parts 5, l, S and 9 will need to be used, but in exceptional cases, where the temperature induced elongation may be greater than usual, it is taken care of by duplicating the self-adjusting units.

Under direct static pressure of a push rod iii, or of a valve stem [3 in the structures shown in Figs. 3 and 4, the two members 8 will not move apart, the angle of approximately 9 not providing a sufficiently strong horizontal component of the spring force to separate the two members 8 from each other. But under the vibratory and other effects of the engine in operation, particularly the valve movements thereof, such separation will occur when the force of the valve spring is applied, so that their movement apart continues until the valve is closed, and the force of the spring acting thereon is removed.

The cost of manufacture of the tappet made in accordance with my invention is lower than hydraulic tappets, while serving all of the desirable functions thereof. Such tappets may be used to replace either mechanical or hydraulic tappets in the case of repair of engines in operation, or may be used for initial engine equipment. Some hydraulic tap-pets include tappet bodies identical with those shown in Figs. 1, 2, and 4 and only the hydraulic equipment or mechanism located in the upper part of the body need be thrown away and replaced with the parts 5, l, 8, and 9 when used with overhead valves, or such parts plus the selflocking screw H and its sleeve I6 in engines having valves of the other type, as shown in Fig. 3.

In exhaustive tests which have been carried out with this tappet, exceptionally satisfactory results have been obtained. There is an elimination of the initial very short time of tappet noises which now sometimes occur with regular hydraulic tappets and, apparently, a small increase in the efiiciency of the engine believed to be due to eliminating the slight leakage or seepage of oil which is continuous in a hydraulic tappet and which must be continuously resupplied durin engine operation.

The invention is defined in the appended claims and is to be considered comprehensive of all forms of structure coming within their scope.

I claim:

1. In a tappet, a cylindrical hollow tappet body having an axial bore, the body being open at its upper end and closed at its lower end, a supporting member circular in outline located within the body at a fixed position therein, having a horizontal lower side and having an upper side with surfaces extending downwardly and outwardly at an angle approximating 9 to the horizontal, a plurality of movable members each having an arcuate outer edge of the same radius of curvature as that of the axial bore, said members being disposed in the same horizontal plane, one located against each of said inclined surfaces, having lower correspondingly inclined engaging sides to bear against said inclined surfaces of the supporting member, the upper sides of said movable members lying in a horizontal plane, a disc member within the hollow body over said movable members adapted to have the pressure of an internal combustion engine valve stem or valve operating push rod thereagainst, and yielding means normally moving said movable members toward each other when free to do so, but permitting said movable members to move away from each other, under vibratory engendered forces of engine operation when the tappet, adapted to be used in an internal combustion engine, is operated therein.

2. A structure as defined in claim 1, said movable members having grooved arc-shaped outer vertical sides around and in the grooves of which an endless light strength coil tension spring is located which, under tension, tends to move said movable members toward each other.

JOHN W. HUMPHREYS.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Re. 21,802 Russell May 13, 1941 1,123,142 Rich Dec. 29, 1914 1,531,909 Engemann Mar. 31, 1925 FOREIGN PATENTS Number Country Date 423,622 Great Britain Feb. 5, 1935 

